Depending on branch wall thickness a single bevel groove with a cover fillet may be required on heavier wall intersections, however the weldment chosen must not penetrate the headers pressure wall excessively... obviously the situation must take into account the pressurized header.
George McKinney <gmckinney@augustaeng.com> wrote: Chris: Not usually grooving the existing pipe - at least not in my experience. You "fish mouth" the tap pipe to conform to the OD, and bevel it. Clean/weld prep the existing pipe, and clamp the new stub in place. Do a single side fillet weld. (Possible reinforcing pad, also). Normally, the tap pipe will have a flange for adding a full open valve, or a full open valve is welded to end, which is just a short section. You are basically making a "tee" here. Then, with the valve in place, the cutting tool is attached to outlet of valve. This is a pressurized type cutting tool, which will extend to the base pipe surface and cut out the approximate ID coupon, and will contain the coupon and pressure when it cuts through. It then retracts back into its housing, close the block valve, depressurize and remove the tool. VOILA - a new tee and block valve. Obviously, you reduce line presssure and flow as much as possible, but I still would like to see an automatic machine that could make that root pass! I'd rather see machine parts flying through the air than human parts....
George McKinney
Augusta Engineering & Design, Inc.
----- Original Message -----
From: "Christopher Wright" <chrisw@skypoint.com>
To: <PipingDesign@yahoogroups.com>
Sent: Thursday, December 15, 2005 12:25 AM
Subject: Re: [PipingDesign] Re: Hot Tapping
>
> On Dec 14, 2005, at 11:13 PM, aluser2 wrote:
>
> > Thats right, its welding from one side, the outside only.
> > wonder what the Sif goes up to when the cutting head gets a more blunt.
> So if I get it right,
> There's a tool that cuts a groove in the pipe wall such that
> --The groove ID about equals to the ID of the branch coupling
> --The groove OD is flared forming a single bevel weld groove
> --The groove follows the surface of the pipe to provide a uniform
> depth.
> The branch fitting rests in the groove while the weld is completed
> After the weld is completed another tool fits in the branch fitting and
> cuts out the opening diameter.
> --I understand a valve body is installed on the end of the branch
> fitting, the hole is cut and then the cutting tool is partly withdrawn
> while the valve is assembled and closed. The the tool is removed form
> the end of the branch fitting.
>
> Is that close?
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@skypoint.com | this distance" (last words of Gen.
> ........................................| John Sedgwick, Spotsylvania
> 1864)
> http://www.skypoint.com/~chrisw/
>
>
>
>
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[Non-text portions of this message have been removed] Received on Tue Dec 27 15:19:00 2005
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